With the development of display technology, various products with display devices appear in daily life, such as mobile phones, tablet computers, televisions, displays, notebook computers, digital photo frames, navigators and the like.
Currently, the mainstream display devices in the market comprise thin film transistor liquid crystal displays (TFT-LCD for short). A display panel in TFT-LCDs generally comprises an upper polarizer and a lower polarizer. The upper polarizer is attached to the light emergent side of the display panel, the lower polarizer is attached to the light incident side of the display panel, and the absorption axis of the upper polarizer and the absorption axis of the lower polarizer are perpendicular to each other. The polarizer can absorb light parallel to the absorption axis and transmit light perpendicular to the absorption axis. The light incident on the display panel firstly passes through the lower polarizer, then changes its polarization direction in the liquid crystal layer, and finally exits through the upper polarizer. In different display units, the degree of change of the polarization direction by the liquid crystal layer is different, which causes the degree of absorption of light by the upper polarizer different, and then the luminance shown by different display units is different, achieving the purpose of displaying images on the display panel.
In this process, both the upper polarizer and the lower polarizer absorb light through the absorption axis, resulting in lower light transmittance.